How come my keyframes don't show up in graph editor?
Both the dopesheet and the graph editor have some options for what they display.



With the cursor button highlighted, only selected items will be shown, for a node tree this means the node that has keyframed values needs to be selected. As you are creating them by script you can set the select property of each node as you create them.

eg. 

bpy.data.materials['Material'].node_tree.nodes['Emission'].select=True


The ghost allows you to see items that are hidden, that is the object containing the keyframes is hidden in the 3dview.

The filters list allows you to show or hide based on what data blocks have the keyframes. By turning off the node symbol you won't see any keyframes from nodetree items.